The present invention relates to a novel negative-working chemical-sensitization photoresist composition or, more particularly, to a negative-working chemical-sensitization photoresist composition capable of giving, with high photosensitivity, a patterned resist layer having excellent pattern resolution and heat resistance and having an excellently orthogonal cross sectional profile.
It is a remarkable trend in recent years that the photolithographic patterning process in the manufacture of semiconductor devices and liquid crystal display panels is conducted by using a chemical-sensitization photoresist composition, which is a photoresist composition of the type utilizing the catalytic activity of an acid generated in the resist layer from a radiation-sensitive acid-generating compound when the resist layer is pattern-wise exposed to actinic rays so that patterning of a photoresist layer can be accomplished with high photosensitivity and excellent pattern resolution in a high efficiency even when the exposure dose is relatively small.
Chemical-sensitization photoresist compositions are classified into positive-working and negative-working photoresist compositions as is reported in Japanese Patent Kokai 2-154266, 6-43647, 6-67433 and elsewhere, of which the negative-working photoresist compositions, which form a patterned resist layer in the areas pattern-wise exposed to actinic rays by crosslinking, are preferred when the patterned resist layer is desired to have high heat resistance. However, negative-working chemical-sensitization photoresist compositions are not quite satisfactory in all respects because, when a novolak resin is used as the resinous ingredient, high pattern resolution and heat resistance cannot be obtained and, when the acid-generating agent used is a compound which releases hydrogen halide as the photoacid, the cross sectional profile of the patterned resist layer cannot be excellently orthogonal.
Accordingly, proposals have been made in Japanese Patent Kokai 6-236024 as a remedy of the above mentioned defects, according to which the heat resistance and pattern resolution can be improved by the use of a polyhydroxystyrene resin in place of a novolak resin. An improvement in the cross sectional profile of the patterned resist layer can be accomplished by the use of sulfonium compound as the photoacid-generating agent. The improvement obtained by these methods is still insufficient because the cross sectional profile of the patterned resist layer is sometimes upwardly narrowing trapezoidal form with rounded shoulders to be far from most desirable orthogonality.